Go solution to Distinct powers - Problem 29 - Project Euler.

Go solution to Number spiral diagonals - Problem 28 - Project Euler.

Go solution to Names scores - Problem 22 - Project Euler.

Go solution to Counting Sundays - Problem 19 - Project Euler.

Go solution to Pandigital products - Problem 32 - Project Euler.

Go solution to Coin sums - Problem 31 - Project Euler.

Naive method for primality test in Go: Given a natural number n, if n is divisible by any number from 2 to square root of n, then n is composite. Otherwise n is prime.

Calculate politeness of a number online, i.e., the number of ways it can be expressed as the sum of consecutive integers.

Calculate politeness of a number in Go, i.e., the number of ways it can be expressed as the sum of consecutive integers

Online tool for prime factorization and calculating sum of proper divisors. The algorithm is implemented in JavaScript and UI in Vue.js.

Go solution to Digit fifth powers - Problem 30 - Project Euler.

Online tool that helps you do prime factorization. The algorithm is implemented in JavaScript and UI in Vue.js.

Sieve of Eratosthenes is a simple and ancient method to find prime numbers up to a given limit. Given a limit, this online demo returns all prime number below the limit.

Online demo of sieve of eratosthenes via Go/GopherJS/gopherjs-vue.

Euler's Totient Function φ(n) counts the positive integers that are relatively prime to n. This online demo use naive method to calculate φ(n) and positive integers coprime to n.

Goldbach's conjecture - Every even integer greater than 2 can be written as the sum of two primes. Given a positive even integer, this online demo returns the two primes.

JavaScript implementation of Sieve of Eratosthenes.

Go solution to Project Euler.

Go solution to Quadratic primes - Problem 27 - Project Euler.

Check if a large number is divisible by 3 or not in Go. This exercise is good example for type casting between int and string in Go.

2n + 1 = p + 2q always has a solution in primes p and q (not necessarily distinct) for n > 2. This online demo finds p and q for given odd number greater than 5. The demo is written in Go and compiled to JavaScript using GopherJS.

2n + 1 = p + 2q always has a solution in primes p and q (not necessarily distinct) for n > 2. This online demo finds p and q for given odd number greater than 5.

2n + 1 = p + 2q always has a solution in primes p and q (not necessarily distinct) for n > 2. Write a Go program to find p and q for given odd number greater than 5.

Test if a number (at least 2-digit) is Lychrel number or not under limited iterations in Go.

Go solution to Non-abundant sums - Problem 23 - Project Euler.

Hard to believe that I don't remember seeing Descartes' rules of signs before -- you'd think this is impossible given the time I spent on ...

Go solution to Number letter counts - Problem 17 - Project Euler.

Spell numbers from 1 to 1000 in English via Go programming language.

This is the last of a small series of similar and basic results in convex geometry.

Go solution to 1000-digit Fibonacci number - Problem 25 - Project Euler.

Go solution to Factorial digit sum - Problem 20 - Project Euler.

Multiplication of big natural numbers in Go. This is for very large positive integers which overflows the built-in numerical type in Go.

Go solution to Power digit sum - Problem 16 - Project Euler.

Go solution to Lattice paths - Problem 15 - Project Euler.

Go solution to Large sum - Problem 13 - Project Euler.

Addition of big natural numbers in Go. This is for very large positive integers which overflows the built-in numerical type in Go.

Previous I used Caratheodory's theorem to prove Radon's theorem, now I'm going to prove the former.

Go solution to Largest product in a grid - Problem 11 - Project Euler.

I came across Radon's theorem the other day, and found this proof. It must have been discovered before.

Go solution to Even Fibonacci numbers - Problem 2 - Project Euler.

Go solution to Multiples of 3 and 5 - Problem 1 - Project Euler.

This is not hard but still interesting. A spread of an array of numbers is the difference between its maximum and minimum. Given an array...

I heard this is classic, but turns out not too hard.

This is also an interesting result, although it's quite simple.

For (iin{1,2,3}), there are (2n+i) integers consisting of (n+i) unique ones.

A simple yet surprisingly interesting result.

There are 2n+1 coins each associated with a weight. When we remove any coin, we can split the rest into two piles each with n coins...

Given a sequence of (n) integers (a_1,ldots,a_n), we map it to ...

On the 2D plane there are (n) blue and (n) red points, no three of them are co-linear. Then we can always pair a blue point with a red ...

Given a natural number (integer), calculate the number of divisors of it in Go programming language.

Go solution to highly divisible triangular number - Problem 12 - Project Euler.

Go solution to largest product in a series - Problem 8 - Project Euler.

Go solution to sum square difference - Problem 6 - Project Euler.

Go solution to longest Collatz sequence - Problem 14 - Project Euler.

Go solution to summation of primes - Problem 10 - Project Euler.

Go solution to 10001st prime - Problem 7 - Project Euler.

Goldbach's conjecture - Every even integer greater than 2 can be written as the sum of two primes. Given a positive even integer, write a Go program to find the two primes.

Euler's totient function implementation in Go programming language.

Find least common multiple (LCM) by greatest common divisor (GCD) via Go programming language.

Go solution to smallest multiple - Problem 9 - Project Euler.

Go solution to special Pythagorean triplet - Problem 9 - Project Euler.

Go solution to amicable numbers - Problem 21 - Project Euler.

It is said to be well-known, but perhaps I've never seen it before:

Let (A(n)) denote the number of sequences (a_1ge a_2gecdots{}ge a_k) of positive integers for which (a_1+cdots+a_k = n) and each ...

We call a (5)-tuple of integers arrangeable if its elements can be labeled (a, b, c, d, e) in some order so that (a-b+c-d+e=29). Deter...

Integer exponentiation in Go programming language.

Calculate the sum of all proper divisors (factors) of an integer number in Go programming language.

Go solution to largest prime factor of 600851475143 - Problem 3 - Project Euler.

Compute the greatest common divisor (GCD) via Euclidean algorithm in Go programming language.

Prime Factorization - Find all prime factors of a given integer number in Go programming language.

I found a different solution to the second part of this problem. We define a chessboard polygon to be a polygon whose edges are situate...

Go solution to largest palindrome made from the product of two 3-digit numbers. - Problem 4 - Project Euler.

Let (m_1, m_2, ldots, m_n) be a collection of (n) positive integers, not necessarily distinct. For any sequence of integers (A = (a_1...

The problem is rephrased. Q: A diamond of size n consists of 2n rows of nodes with lengths from top to bottom being 1, 3, 5, ..., 2n-1...

Let (P_1, P_2, dots, P_{2n}) be (2n) distinct points on the unit circle (x^2+y^2=1), other than ((1,0)). Each point is colored eit...

Go implementation of primality test - optimized school method.

Go implementation of Sieve of Eratosthenes.

In a mathematical competition some competitors are friends. Friendship is always mutual. Call a group of competitors a clique if each two of...

There are n>=2 line segments in the plane such that every two segments cross and no three segments meet at a point. Geoff has to choose an ...

International Mathematical Olympiad (IMO) 2014 Problem 6

Asian Pacific Mathematics Olympiad (APMO) 2015 Problem 4

International Mathematical Olympiad (IMO) 2010 Problem 6

International Mathematical Olympiad (IMO) 2015 Problem 6

In a recent algorithmic coding contest which I didn't do well, the hardest problem killed me. It distinguished me from other superior coders. But it's still an interesting one. The problem is essentially to solve a 0/1 knapsack problem on a tree where each node is associated with an …

United States of America Mathematical Olympiad (USAMO) 2015 Problem 3

The infamous Grasshopper problem

Evaluate Multivariate Normal Distribution with NumPy in Python.